There exists an ongoing demand for procedures to improve skin defects. These defects may include wrinkles, old or loose skin, irregular pigment distribution, sun damaged skin and other defects formed on or in the skin tissue surface. Heretofore, such skin defects have been treated by two general approaches using energy based devices, 1) Full area skin resurfacing and 2) Fractional skin resurfacing.
Full area skin resurfacing treatments involved treating the entire surface of the effected skin. Both ablative and non-ablative energy sources were used, producing a full area injury that would promote healing and new collagens restoring the structures lost due to the skin defects. The ablative variety would use continuous scanning devices to remove the upper portion of the skin and the resultant healing response would, under the right conditions, produce a very good result. Such techniques were very aggressive, were painful to the patient, would have lengthening recovery times where patients had to avoid sun exposure, and had a potential for complications. The non-ablative full area skin resurfacing mode would heat the deeper dermal layers without heating the upper epidermis. By cooling the surface of the skin and focusing electromagnetic energy such as that from a laser device, a selected dermal damage region can be achieved while leaving the epidermis undamaged. This modality exhibited lower recovery times but lacked efficacy when compared to the ablative approach. At times, both ablative and not ablative treatments are combined to produce desired curative results to the skin tissue
Fractional skin resurfacing was recently invented, in which a pulsed laser scans a tissue area to create a discrete pattern of ablative or non-ablative lesions leaving untreated areas of skin, theoretically treating only a fraction of the skin, which would heal faster than the previous full area resurfacing method. During this healing process, new skin is formed and new collagen forms, resulting in reversing the appearance of the skin defects. It is important to keep the volume of treated skin low to keep the healing response controlled and to avoid creating complications. Once a channel has been drilled into the skin surface, it is known to further treat the subsurface skin by performing a non-ablative treatment under which the interior surfaces of the channel as well as a bottom of the channel are heated to a degree to cause collagen remodeling. Such techniques are disclosed in U.S. application Ser. No. 13/314,548, an application assigned to the assignee of the present invention.
Of these two approaches, in terms of downtime and safety, due to limited exposure to complications, the fractional skin resurfacing approach is preferred, however, the efficacy of the full resurfacing approach is preferred. It is hypothesized that a ratio of optimized smaller spots, or shapes, can be created in an optimized fractional skin resurfacing modality to decrease the downtime, provide more comfort to the patient, and improve the efficacy over the devices of today. The challenge is the technological limitations of present day laser devices which do not permit the formation of very small narrow channels in a practical way. An optical configuration in a laser scanner may be created to be able to focus the treatment beam into a small focal point but the solution would involve more expensive optics, could require a short focal length complicating the scanner design by forming the optics to be too close to the targeted skin area and the scanner and raise the potential for debris contamination of the optics. What is needed is an apparatus and method for producing very small channels in tissue. It is to this goal that the present invention is directed.